1. Field of the Invention
The present invention relates to an apparatus for drying cleaned plate-like workpieces by removing a cleaning solution from the workpieces.
2. Description of the Prior Art
There has been known an apparatus for drying workpieces, such as small thin ceramic plates for use as crystal oscillators or capacitors, which have been cleaned by a cleaning apparatus using a cleaning solution such as water. In such an apparatus, a plurality of workpieces are placed in a tray having an air-permeable bottom, and hot air is applied from above the tray and drawn from below the tray so that the hot air forcibly passes through the spaces between the workpieces. The hot air is heated to such a temperature that it can evaporate the cleaning solution that is attached to the workpieces.
The hot air which is supplied from a hot-air duct can not only evaporate moisture from the exposed surfaces of the workpieces in the tray, but also remove moisture in spaces or gaps between those workpieces which may overlap each other as the hot air enters those gaps.
Before the workpieces are dried by the drying apparatus, the workpieces are cleaned by the cleaning apparatus. If the workpieces are small thin lightweight ceramic plates for use as crystal oscillators or capacitors, for example, and cleaned ultrasonically while being supported on a tray and immersed in a cleaning solution, then when the tray is taken out of the cleaning solution, the workpieces in the tray tend to be stacked into blocks in which they stick closely together through the attached cleaning solution. The gaps between the workpieces in each of the blocks are very small, with the cleaning solution firmly retained in the gaps. The gaps between the blocks of workpieces are larger than the gaps between the workpieces, and may sometimes be large enough for them to be interconnected vertically in the tray.
When the cleaned workpieces are dried by the drying apparatus, hot air supplied from the hot-air duct tends to pass through the larger gaps between the blocks of workpieces, rather than being uniformly applied to the workpieces in the blocks. Since the heat of the hot air cannot efficiently be transmitted to the workpieces sticking together in the blocks, it takes a relatively long period of time for all the workpieces to be fully dried.